1. Field of the Invention
Embodiments of the present invention relate to structural systems or structures comprising a flexurally deformed panel.
2. Description of Related Art
Structural systems involving more than one panel connected together are commonplace, for example folded plate roofs, boxes, etc. Connecting two originally planar elements together, one of which is substantially deformed, is also known. For example, corrugated paper or card comprises a sheet of plane paper or card which is deformed by means of pressure, heat and water content (but not flexural stress) into a corrugated shape, for example of sinusoidal cross-section, and is then adhered by gluelines to one or two plane sheets of paper or card. However, in the case of corrugated paper or card, the corrugated element is typically deformed in a material state and under conditions such that, were it not attached to the one or more planar sheets, it would still be corrugated in repose. Corrugated plastic constructions, such as Correx® a trademark of Kaysersberg Plastics, a part of D S Smith (UK) Ltd. are made by extrusion, not flexural deformation of the core.
Tied members which are deformed within the elastic range are also known, for example the common bow for projecting arrows, which typically comprises a substantially linear member of wood or a laminate of several materials, which is flexurally deformed and tied at each end by the string of the bow.
Point-of-purchase display devices are also known in which a substantially vertical filmic display is tensioned by one or more bowed linear prop members, typically fixed to and flexed between a heavy base, to which the bottom of the display film is also attached, and a cross-member at the top of the display panel. The bowed prop members are made slightly longer than the display film and are flexurally deformed to induce tension in the display film to keep it flat or plane. A heavy base is required for lateral stability of these systems.
Panels flexed and restrained between two points of a relatively very rigid member are also known, for example, flexed acrylic or other plastic sheets within some light fittings.
British Patent Application No. 8510775 “Constructional Member of Variable Geometry” (Hill and Higgins) discloses substantially linear members comprising interlocked, substantially linear components that can be flexurally deformed and fixed in their deformed geometry by means of discrete mechanical fixings.
In the field of building structures, tied arches and vaults are known, as are flitch beams, slabs, arches and vaults with prestressed ties. Curved and tied building structures are disclosed in U.S. 16,767, U.S. Pat. No. 1,687,850, U.S. Pat. No. 1,762,363, U.S. Pat. No. 1,963,060, U.S. Pat. No. 2,237,226, U.S. Pat. No. 2,287,370, U.S. Pat. No. 2,360,285, U.S. Pat. No. 3,057,119, U.S. Pat. No. 4,536,997 and U.S. Pat. No. 5,595,203.
U.S. Pat. No. 4,865,111 and U.S. Pat. No. 4,979,554 disclose flexed, tied panels forming the ends of a display system.
U.S. Pat. No. 6,311,709 discloses a self-erecting, collapsible fabric dome structure comprising resiliently flexible wire.
U.S. Pat. No. 5,313,666 discloses a flexed panel facial sunshield apparatus.
U.S. Pat. No. 2,160,724 and U.S. Pat. No. 2,862,322 both disclose opaque displays in an assembly comprising an opaque curved card element and a plane element which is “D” shaped on plan, to provide a stable display assembly. The curved and plane components are connected by means of folded card tabs, which will inevitably open up in use and cause reduction of any tension in the plane element. U.S. Pat. No. 5,619,816 discloses a flexed display assembly with string ties. U.S. Pat. No. 6,276,084 and U.S. Pat. No. 6,772,069 disclose means of restraining a display panel in a curved shape.
U.S. Pat. No. 4,749,011 and U.S. Pat. No. 6,065,512 disclose a flexed panel for opening up a flexible bag.
Zips to join two pieces of plastic together are known. U.S. Pat. No. 6,540,085 (Davies) discloses plastic zips comprising teeth attached to side panels and a sliding connector, the side panels typically being heat bonded to a plastic film material being joined.